Finally here, the song children across America know by heart, "Let it go" from Disney's "Frozen," our parent company. The movie and the song both up for an Oscar tonight, but the real winning performance, perhaps from your own children. One of our resident dads, David Wright, with his own camera rolling. &#9834; The snow flows white on the mountaintop &#9834; Reporter: School's out, and we're on our way to see "Frozen" again. &#9834; Let it go let it go &#9834; &#9834; can't hold it back anymore &#9834; Reporter: My three daughters plus two of their school friends, and they know every word by heart. &#9834; Turn away and slam the door &#9834; &#9834; I can't take it anymore &#9834; Reporter: Across America millions of parents can relate. &#9834; You'll never see me cry &#9834; Reporter: The voice behind the song? Broadway star idina Menzel. She'll be singing "Let it go" at the oscars Sunday night. &#9834; Here I'll stay &#9834; It's about owning your own power. &#9834; Let it go let it go &#9834; Reporter: The husband and wife songwriters nominated for an Oscar tonight say the movie actually grew out of queen Elsa's theme song. She was the villain in the first version of the script, yeah, and once we wrote that song, everyone started thinking of her differently. Suddenly we found that we had a very sympathetic, very real, very universal truth of how we all kind of keep our power hidden, and we fear it. Reporter: The song does cast a spell. We're here. This week disneyland gave our three little princesses a surprise treat. Here we go. A private audience with Elsa and Anna in the flesh. And, of course, this being "Frozen" -- Do you know that song? Yes. Can you sing it for us? &#9834; Let it go let it go can't hold

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